Ketamine addiction

Is it possible to get physically addicted (and get withdrawals when discontinued) from ketamine?

Yes. Ketamine dependence is one of the problems associated with this drug. Some ketamine users become dependent on the drug in a manner resembling cocaine dependence, with craving , high tolerance and loss of ability to manage the use of the drug. Some users take 5-6 grams of ketamine daily and abuse of ketamine becomes the priority in their lives. There is no evidence of a physiological withdrawal syndrome, but this does not mean that dependence is not possible. A minority (estimated 5-8%) of users develop ketamine dependence.
An extensive review about this issue can be found here (pages 166-203)